The present invention relates generally to the fields of polymer chemistry. More particularly, it concerns monovinylarene-conjugated diene copolymers with lower Tg relative to reference styrene-butadiene copolymers.
Articles formed from monovinylarene-conjugated diene copolymers, such as styrene-butadiene copolymers, for example K-Resin® (Chevron Phillips Chemical Co., The Woodlands, Tex.), generally have a number of good physical properties. However, in the case of articles for which heat shrink is a desirable processing step, monovinylarene-conjugated diene copolymers are generally slightly less favorable for use, as their glass transition temperatures (Tg), which is the temperature at which shrinking occurs, are typically in the range of about 95° C. to about 108° C. This relatively high Tg requires the use of a relatively large amount of heat to reach the temperatures at which shrinking occurs.
Therefore, it would be desirable to have monovinylarene-butadiene copolymers with lower Tg and more ready heat shrink processibility.